Rocks for Jocks 101

Iowa Stratigraphic Column, courtesy of Iowa Geological Survey

Since I was trained as a geologist, I’d like to start discussing rocks. Hopefully, I’ll keep this informative, but not too complex. I may be a nerd, but I try not to assume everyone else is.

I find beauty in rocks—a sense of mystery (perhaps because we see so few forming today), as well as, a healthy respect for the firm foundations we walk upon. Every rock, even a common limestone, has a history. How to discover that history is up for debate.

One of the key principles of geology which students learn in the first few weeks of Rocks for Jocks class is called Uniformitarianism. Big word, but simple. Uniform, with an itarianism stuck on the end. Basically, it’s the theory that the geologic processes we see at work in the present are the same as they were in the past. As one of my old professors used to say, “The present is the key to the past.” Many geologists have lived by this rule, and some still do. This, however, always seemed a little off to me. It’s kind of like saying: because I’m sitting on my couch writing this post, I have always been sitting on my couch writing this post.

I guess Stephen Jay Gould thought this theory didn’t make much sense either, because in the 1970’s, he dared to say that Uniformitarianism is not supported by the rock record. And yes, geologists were in an uproar, until they generated a new theory called Punctuated Equilibrium. This name sounds impressive, but what it means is we tend to find groups of animals in different rocks (strata), not a slow continuum as the stratigraphic column would seem to suggest (see stratigraphic column of Iowa above).

Evolutionists believe the animals which are grouped together evolved rather rapidly and are separated by long periods of time with little evolution (long periods of equilibrium punctuated by fast evolution=punctuated equilibrium). Creationists, however, believe the animals are grouped together more by habitat. When Noah’s flood came, the water and sediment buried the animals according to where they lived.

The above is a perfect example of how assumptions guide beliefs. Evolutionists assume change through evolution and long time periods. Creationists assume Noah’s flood and a period of about a year. The evidence (i.e. the fossil rich strata) can be interpreted either way.

Of course, the assumption of long versus short time periods leads to another disagreement between evolutionists and creationists—how long does it takes to form a rock? You would think this would be an easy question to answer, but it’s not. We see sediments accumulating and eroding at a slow rate today. Does that mean it’s always been that way? Only if you want to assume it has.

In fact, during the 1980 eruption of Mt. St. Helens, geologists got a glimpse of catastrophic burial and canyon formation caused by pyroclastic flows (fast moving ash and rock debris clouds) followed by large mudflows. In one day, sediment hundreds of feet thick was deposited and a canyon over 100 feet deep was carved (Austin, S. A. 1986. Mt. St. Helens and Catastrophism. Acts & Facts. 15 (7)).

Similarly, the formation of the other rocks on our planet, thousands of feet thick, occurred on a massive scale that we have a hard time imagining today. But Mt. St. Helens showed us that a massive scale of rocks doesn’t necessarily mean a massive time scale.

What do you think? Is the present the key to the past? What are your assumptions when it comes to earth origins?


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